Offshore mooring chain steel and thermal treatment method for mooring chain

Abstract

The invention discloses offshore mooring chain steel and a thermal treatment method for a mooring chain made of the offshore mooring chain steel. Austenitic grain refining elements in the offshore mooring chain steel comprise 0.006 to 0.024 percent of N by weight, and Al, Nb, Ti and V are precisely cooperated for use. The diameter of the offshore mooring chain is 70 to 210 mm, and a high-temperature quenching-tempering continuous thermal treatment process is adopted; and the furnace temperature of a quenching furnace is greater than 930 DEG C, the highest allowable furnace temperature is 1,150 DEG C, and tempering temperature is 590 to 690 DEG C. According to the offshore mooring chain steel, the potential of an alloy element is developed, the production period is substantially shortened, ideal tissue, substructure and performance can be obtained, and the equipment investment is reduced, so as to pursue the optimal cost performance.

Description

technical field [0001] The invention belongs to the field of heat treatment of low-alloy steel and marine mooring chains, and in particular relates to the composition design and manufacturing process of a class of fine-grained marine mooring chain steels, and in particular to a class of marine mooring chains and a heat treatment method thereof. Background technique [0002] Marine exploration, deep sea oil production, national defense construction, etc. all need mooring systems for positioning and mooring marine floating bodies. The main structure is the steel mooring chain. Mooring chains can be divided into three grades, three and a half grades, four grades, four and a half grades, five grades and six grades according to their strength levels. The tensile strength of chain links at all levels after quenching and tempering is not less than 690Mpa, 770Mpa, 860Mpa, 960Mpa, 1000Mpa and 1110Mpa respectively. The six-level chain is waiting for trial. The applicant has grouped...

AI Technical Summary

Problems solved by technology

[0011] Chinese patent application number 200810033953.2 discloses that the quenching furnace temperature of the mooring chain is less than 1050°C, and there is no means of controlling the maximum chain temperature

In addition, the maximum height of the general inverted U-shaped vertical continuous furnace is only about 4m

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